Universal dynamic traction carriage



Oct. 1, 1968 J. w. CARR 3,403,675

UNIVERSAL DYNAMIC TRACTION CARRIAGE Filed Nov. 16, 1964 M 5Sheets-Sheet, 1

L/OHN 14/. CAez INVENTOR.

I I I g ll .1" 35 mm Mi Oct. 1, 1968 J. w. CARR 3,403,675

UNIVERSAL DYNAMIC TRACTION CARRIAGE Filed NOV. 16, 1964 5 Sheets-Sheet 2i 25 /20 [Ma L/OHN W CA 22 INVENTOR United States Patent 3,403,675UNIVERSAL DYNAMIC TRACTION CARRIAGE John W. Carr, 168 Cronin Drive,Santa Clara, Calif. 95051 Filed Nov. 16, 1964, Ser. No. 411,644 13Claims. (Cl. 128-75) ABSTRACT OF THE DISCLOSURE A compound low inertia,low friction carriage; calibrated spring traction device mounted to theframe of a wheeled sub-carriage which tracks along an elasticallycontrolled vertically deflectable monorail; all components and componentfunctions cooperate to meet the dynamic requirements of an active seatedor bedded patient. When the carriage is operatively mounted with respectto a chair the patient may carry out the usual tasks of a normal seatedworker and thereby be productive while in traction.

This invention is a versatile mechanism adapted for the generalapplication of traction to the human patient in a seated position or inbed.

Most devices presently in use do not allow for freedom of movement ofthe parts of the patients body under traction, or if such movement ispossible, it is usually accompanied by acceleration or decelerationforces reacting on the patient. Even with movable weight tractionsystems the point, relative to the part of the body under traction, fromwhich traction forces are applied, is usually fixed. This puts rathersevere restraints on movements of the portion of the body undertraction.

Wherefore, it is the primary objective of this invention to introduce auniversal'dynamic traction carriage which will not only result inincreased comfort to bed patients subject to traction, but will also,for cervical and lower back and pelvic traction, allow a patient tocomfortably remain at seated work or at other normally seated activitieswhile having therapeutic traction applied. The application of thecarriage for a seated patient is primarily for cervical or lower backand pelvic traction. A system of applying lower back and pelvic tractionto a person engaged in seated activities, including a special suspensionbelt developed particularly for the application of lumbosacral tractionto a seated patient has been introduced elsewhere by this inventor. SeeSer. No. 92,100 filed Feb. 27, 1961, now US. Patent No. 3,167,068.

A use of that belt with the present universal traction carriage will bereferred to in the following description. The present invention isconcerned not with the traction application means to the part of thebody under traction, but rather with the freedom of movement in up tothree dimensions of the point in space from which the applied tractionforces are produced. In addition to this spatial dimensional freedom,use is also made of the application of Hookes law (as introduced in theabove reference by this inventor) to the time domain freedom ofacceleration and deceleration forces by the use of elastic low inertiamembers.

It is recognized by the inventor that various specific combinations ofthe principles herein introduced with those introduced in the abovereference (US. Patent No. 3,167,068) could result in variously differentstructures in detail, but would be only a state of the art variation ofapplication of the principles thus disclosed.

In a typical cervical traction embodiment of the invention the patientis provided with one of the existing cervical head sling apparatus andis seated in a chair. To the back of the chair is attached a verticallydirected linear structural member, the upper end of which extends six toseven feet above the floor on which the chair is stand- "ice ing. Nearthe upper end of this member is attached a hinge or swivel and to themovable side of the hinge is attached, in cantilever, another linearstructural member which, under no load, lies in essentially a horizontalplane and is most conveniently in the form of a metal tube or rod, theoutside curvature of which serves as the track for a circumferentiallygrooved pulley or wheel which is mounted in a U-shaped block. To thebottom of the block it attached a calibrated spring or springs which arethe source of the traction reactive forces. The wheel tracks radiallywith respect to the hinge joint on the upper side of the cantileveredmonorail member. The length and cross section modulus of this hingedcantilever track, which is in this case part of the primary carriage,are chosen so that the vertical downward deflection of the point ofapplication of a load, equal to the prescribed traction forces, on theradially moving wheel (of the subcarriage) is approximately the amountthat a patients chin will vary in elevation as he moves his head fromthe position it has in a normal upright seated position to a normallyrequired forward and downward position as in bending over a desk towrite. Starting with the primary carriage a one dimensional freedom ofmotion from side to side is provided. In this particular example this isan angular motion. (Another method of providing the primary carriagemotion could be, for example, a two wheel carriage on a laterallyoriented rigid track.) The second dimension of mechanical freedom ofmotion is provided by the sub-carriage wheel free to move in a radialdirection with respect to the hinge joint. The third dimension ofmechanical freedom, resulting in complete three dimensional freedom ofmotion of the traction loaded axle of the sub-carriage wheel, isaccomplished in this particular example, by the deflectible cantilevermonorail on which the sub-carriage wheel tracks. When a traction load isapplied to the monorail wheel and these traction forces transmitted to acervical traction sling applied to a patients head, it can readily beseen that the patient has full three dimensional freedom of movement ofhis head in carrying out normal seated activities. Equipping thesubcarriage with a calibrated spring traction, and taking care that themoving parts are of low weight, provides the patient with a low inertiatraction in the four dimensional space-time domain of a dynamic system.Weights, depending from the sub-carriage may be used as the tractionsource. However, now there are inertial forces of acceleration anddeceleration including the impulses of starting and stopping, which mustbe absorbed by the mechanism and the patient.

Specific embodiments of the invention as well as the general versatilityof it will be clearly apparent from the following description andaccompanying drawings.

FIG. 1 is a perspective view of the specific example generally describedabove.

FIG. 2 is an expanded scale drawing of half of a symmetrical springcalibrated traction sub-carriage mechanism operatively mounted to thesub-carriage tracking wheel.

FIG. 3 shows an alternative method of providing a vertically defiectablemonorail on which the sub-carriage wheel tracks. In addition it showsextended bars and vertically depending straps for lower back and pelvictraction application. It also shows that the mechanism may be supportedby a wall or beam bracket rather than being mechanically fastened to thechair.

FIG. 4 shows the application of restricted versions of the device inwhich only two degrees of mechanical freedom may be required by a bedpatient in cervical and/or leg traction.

FIG. 5 shows a bag of weights which may be used in lieu of thecalibrated spring traction.

Referring to FIGS. 1 and 2 a torso 10 of a patient is shown seated on achair 11 at a table 12 with one of a variety of existing cervicaltraction head slings 13 in operative position. A structural member 14 isattached in a horizontal lateral orientation to both rear chair legs. Tothe mid-section 16 of structural member 14- is attached the lower region18 of vertical support member 17. Vertical support member 17 is attachedto the chair 11 at central region 19 of the top portion of back 20 bymeans of a slotted L-section bar 21. The base of the slotted L-sectionis bolted or clamped to the top portion of back 20 and a bolt passesthrough vertical member 17 and the slot in bar 21. The slot provides foradjustment to put member 17 in a vertical position. Hinge 22 is firmlyattached to the upper region of vertical support 17. To the upper partof the rotatable side of hinge 22 is attached an operationally stiffstructural cantilever member 23. To the lower part of the rotatableportion of hinge 2.2 is attached an operationally deflectable resilientcantilever member 24 which, together with the rotatable portion of hinge22, serves as the primary carriage monorail providing azimuthal freedomof motion. A chain 26 of proper length to limit any possible extremedeflections of operationally deflectable resilient cantilever monorail24 is attached to the free ends of stiff cantilever member 23 andmonorail 24 Wheel 25, tracking radially on monorail 24, and bearing thetraction load, provides radial freedom of motion. Clamp 28 can be movedradially on monorail 24 to serve as a rear stop for wheel 25 to therebyadjust the forward angle of traction when the patient is erect. Inaddition clamp 28 connects to chain 29 which in turn is movablyconnected to stiff cantilever member 23. Chains 29 and 26 thus provide asafety device in case member 24 should ever break at the point ofhighest stress 30. Monorail 24, operationally deflectable within itselastic limit under normal traction load, provides the verticaldimensional freedom of motion. In selecting monorail '24- structuralanalyses of the resultant single point loaded cantilever structure mustbe made taking due consideration of the amount of vertical deflectionrequired under a given average traction, maximum moment, maximum stressat point 30 of member 24 as a result of this maximum moment, and thetotal dynamic nature of the operational stresses including fatigue undercontinued cyclic usage. The same applies for the possible high peakloads on operationally stiff cantilever member 23. Pin 27 serves as astop for block 31 which is operationally connected to wheel 25 by axlepin 32. Swivel pin 34 connects bars 33 to block 31. Spring support tubes35 ar inserted into holes in bar 33 and held by set screws 36. From pins37 in the upper end of support tubes 35 depend extension springs 38, thelower ends of which are mechanically ganged together by gang bar 39connected to the lower ends of the springs 38 by links 40 through holes41 in bar 39. Spring housing tubes 43 are attached to bar 39 by pins 44through holes in the walls of the tubes and through holes 42 in the bar.Light chain 45 is adjustably hooked to the center of gang bar 39 viahook 46. Either spring housing tube 43 is calibrated with numbers 47 toindicate the amount of traction being applied. The lower end of chain 45is operationally connected to the spreader bar 13a of a conventionalcervical traction sling 13.

The fundamental operational nature of the carriage is now quite evident.A patient wearing traction sling 13 seats himself in chair 11. He thenreaches up and hooks sling 13 to the ends of spreader bar 13a, chain 45having been set at the correct linkage to hook 46 to provide theprescribed amount of traction as indicated by numbers 47 on one of thespring housing tubes 43. Clamp 28 has previously been adjusted for thedesired angle of traction when the patient is in an erect position. Asthe patient 10 moves back and forth, wheel 25 tracks on monorail 24which deflects in increasing increments as wheel 25 moves radiallyoutward from the hinge. The downward deflection for a constant load onthe cantilever monorail of constant cross section is proportional to thedistance from hinge 22 to the center of wheel 25 raised to the thirdpower. This tends to keep the distance between wheel 25 and spreader bar1311, on the head sling 13, constant,

thereby resulting in essentially constant spring tension which bears aconstant relationship with the traction applied. The angular motionprovided by the hinge 22 allows the patient 10 to move his head fromside to side, likewise without increasing or decreasing spring tension.Swivel pin 34 allows patient 10 the freedom of twisting his torso orhead without encountering any resistive forces. Good design seeks tokeep the weight of all members loading wheel 25 at a low value to makethe effect of their mass inertial actions on the patient small, andthereby take maximum advantage of the spring applied tension principle.

Referring to FIG. 3 hinge 111 is attached to partition clamp 112 so thatthe traction system may be supported along the top edge of a partitionwall. Hinge 111 could as well be attached directly to a flat wallsurface. The assembled mechanism shown supported by wheel 25 is in everydetail identical to that fully described previously in the descriptionrelative to FIGS. 1 and 2. The method of obtaining the primary carriagemotion in this example is the same as that in FIG. 1. To hinge 111 isattached radial operationally rigid cantilever member 114 havingvertical projection 114a at its free end to support extension spring115. The monorail 113 on Which wheel 25 tracks, is rotatably mounted ina vertical plane to hinge 111 by means of a rotating joint 116. Theother end of monorail 113 which is operationally essentially stiff inthis application is supported by extension spring 115. Chain 117prohibits extreme deflections and/or possible breakage of spring 115.Pin 118 and clamp 119 serve the same functions as pin 27 and clamp 28 ofFIG. 1. In this example as the sub-carriage wheel 25 moves radiallyoutward under load the end of monorail 113 supported by spring movesdownward increasingly as wheel 25 moves radially outward from hinge 111.In this example, if spring 115 is linear and manufactured without anyinitial tension, the amount of vertical deflection under constant loadon wheel 25 will be directly proportional to the distance between hinge111 and the center of wheel 25. However, if the spring is linear andfabricated with initial tension then a given load on wheel 25 will haveto be moved radially far enough out from the hinge 111 to overcome theinitial tension before downward vertical deflection takes place. Thespring constant of spring 115 and the amount of initial tension inspring 115 can both be designed to give the approximate requireddeflection for operation. By using stiffer springs (38 in FIG. 2) and astronger extended bar 120 (39 in FIGS. 1 and 2), and strong spring 115,stronger stiff cantilever member 114, and stronger monorail 113, thecarriage can be adapted for lower back and pelvic traction. Straps 121,adjustable in length by friction buckles 122, are fastened to bar 120 bybeing threaded through slots 123 and have hooks 124 depending from theirlower ends. The hooks 124 are detachably connectable to a suspensionbelt worn about a patients lower thoracic region. The belt is equippedwith traction engagement rings located directly under the patientsarmpits. This belt has been disclosed in Ser. No. 92,100, filed Feb. 27,1961, now U.S. Patent No. 3,167,- 068.

Other types and uses of elastic members can be used to obtain similaractions to those discussed. For example, it will be noted that the mainvertical structural member 17 to which the hinge 22 in FIG. 1 isattached could also be chosen to be increasingly defiectable under anincreasing load moment and thereby provide a portion of the necessarydeflection of the applied load point on the subcarriage, the hingeitself would move forward as the patient moved forward and downward.Also the monorail could be a rigid member supported by a compression ortorsion spring or torsion bar at the hinge. Also, for example, amultiturn torsion spring housed and mounted to the sub-carriage wheelcould be used to obtain the traction in lieu of the extension springs38, spring housing tubes 43, and spring support tubes 35 of FIGS. 1 and2.

Refer now to FIG. 4 where simplified versions of parts of the basiccarriage may be used to apply, for example, cervical and/or leg tractionto a patient in bed. Only two dimensional mechanical freedom of motion,maintaining constant traction, is shown here, but the more complicatedthree dimensional freedom carriage can be used for these applications ifdesirable.

In FIG. 4 patient 200 is supported in a semi-seated position in bed 201by elevated section 202. Bed 201 is equipped with a rectangular frame203 of conventional type. Refer first to the cervical traction device.Carriage support 204 is fastened to frame 203 by clamp 205. Hinge 206 isattached to the lower portion of carriage support 204. To the rotatableportion of hinge 206 is attached, in cantilever, operationally rigidlinear structural members 207 and 208. These two members rigidlyfastened to each other at the free ends by spacer 209 and bolt 210 forma rigid box-like complex cantilever beam which, with the hinge,constitutes the primary carriage providing azimuthal freedom of motionwith respect to support 204. Lower member 208 of this structure is mostconveniently fabricated from right circular cylindrical tubing or rod tobest serve as a rail. Wheel 209a mounted in block 210a constitutes thesecondary carriage, providing radial motion with respect to hinge 206and support 204. On block 210a is attached an extension spring 212 and athin strip of metal 211 on which spring traction calibration marks 213are placed. Chain 215 adjustably linked to hook 214 on the lower end ofspring 212 provides adjustable traction applied to cervical tractionhead sling 216 operationally attached to patient 200.

Refer now to the leg traction in FIG. 4. Carriage support 250 is rigidlyfastened to frame 203 by clamp 251. Support 250 has several sets ofholes in the lower portion drilled in paired matched alignment with theholes in the stationary portion of hinge 252 so as to allow for verticaladjustment of hinge 252. To the moving portion of hinge 252operationally rigid linear structure members 253 and 254 are attached incantilever and rigidly fastened together by spacer 255 and bolt 256.Together with the moving part of hinge 252 this structure provides forazimuthal rotation and constitutes the primary carriage. Member 253 isextended to provide a radially long arm. On 253 is mounted extensionspring 257 which is attached at one end, 258, to member 253, and at theother end 259 to rope 260. Spring calibration marks 257a indicate theamount of traction applied. Rope 260 extends over pulley 261 whichrotates on shaft 262 attached to the extended end of member 253. Theother end of rope 260 is adjustably link connected to foot sling 264operationally attached to patient 200. Wheel 265 in block 266constitutes the sub-carriage means which gives radial freedom of motionwith respect to carriage support 250 and hinge 252. D ring 267 isconnected to block 266. Web strap 268, adjustable in length by frictionbuckle 269 threads through D ring 267 at the pulley block and hook 270at the lower end, which is detachably connectable to knee support sling271.

Thus it is depicted how two two-dimensional carriages can be adapted toapply cervical and leg traction simultaneously to a patient in a bed,with the patient retaining maaility of head and shoulders and of the legunder traction. Of course the two types of traction can be usedseparately for leg or cervical traction, or for applying traction toother parts of the body.

Referring to FIG. 5 bagged weights 300 are connected to rope 302 bycoupling 301. Extended member 305 is member 253 in FIG. 4. Pulley 303 isrotatably attached to 305 by shaft 304. Rope 302 passes over pulley 303and is coupled to foot sling 306 which is operationally attached to apatient.

It is obvious that weights may be used with any of the traction typesshown in lieu of the springs.

Placement of the operationally rigid structurally stiff cantilevermember in FIG. 1 and FIG. 3 could be to either side of or below thedefiectable monorail. Various other means of limiting the defiectablemember could be used.

The defiectable monorail 24 in FIG. 1 and 113 of FIG. 3 could be held ina deflected position and fastened rigidly at both ends to the stiffcantilever member or it could be a permanently formed rigid structurehaving one or more formed rails.

For such applications as may require the patient to be standing thecarriage mechanism shown in FIG. 1 and FIG. 3 may be supported by anyconvenient supporting structure such as a wall, ceiling, or table, thechair not being necessary. For instance this may be used by a draftsmanstanding up at a drafting board, in which case a primary andsub-carriage means each tracking respectively along the X-Y coordinatesof a cartesian coordinate system, with two ends of the primary carriagesupport fastened to the ends of a drafting table or board, couldconveniently be used.

The attachment of the vertical support to the rear of the chair as shownin FIG. 1 is convenient, but the vertical support could as well becomposed of two or more members attached, for instance, to the sides ofthe chair or other seating means.

I claim as my invention:

1. A passive mechanism, for applying cervical, lower back, or legtraction to a patient, comprising a primary carriage operativelyconnectable to a carriage support means above a bed or a chair, a trackconnected to and supported by said primary carriage, a wheeledsubcarriage operatively connected to and constrained to move along saidtrack, traction means operatively connected to said sub-carriage,tension transmitting means operatively connected to said traction meansand operatively connectable to a traction application means on apatient.

2. A passive mechanism, for applying cervical or lower back and pelvictraction to a seated patient, comprising a vertical support memberoperatively connected to a chair, primary carriage and carriage supportmeans operatively connected by means of a hinge to said vertical supportmember, a track connected to and supported by said primary carriage, awheeled sub-carriage operatively connected to and constrained to movealong said track, calibrated spring traction means operatively connectedto said sub-carriage, tension transmitting means operatively connectedto said traction means and operatively connectable to a cervical orlower back traction application means on a seated patient, allconstituent parts and part functions cooperating with said tractionapplication means on said patient to permit said patient to make normalseated body and limb movements to perform the normal work functions of anormal seated person while he is under essentially constant traction.

3. A passive mechanism, for applying traction to a patient, operativelyconnectable to a mechanism support means, comprising primary carriagemeans free to move along one coordinate in an essentially horizontalplane, a monorail track operatively connected to said primary carriagemeans with its no load orientation extending in essentially a horizontalplane at essentially right angles to the line of motion of said primarycarriage means, said monorail track operatively defiectable under loadin a vertical plane in a manner providing elastically controlledincreasing downward vertical deflection of a point on said monorailwhere said load is applied as the distance from said point to one end ofsaid monorail increases, wheeled subcarriage operatively connected tosaid operatively defiectable monorail and constrained to track along aportion of the length thereof, traction means operatively connected tosaid sub-carriage means and operatively connectable to a tractionapplication means on a patient when a patient is operatively positionedwith respect to said carriage means.

4. A passive mechanism, for applying lower back or cervical traction toa seated patient, comprising a chair, vertical support means operativelyconnected to said chair, a horizontal primary carriage operativelyconnected to said vertical support means and free to move from right toleft with respect to said chair, a track operatively connected to saidprimary carriage with its no load orientation in a horizontal plane atright angles to the line of motion of said primary carriage, said trackoperatively deflectable under load in a vertical plane in a mannerproviding elastic controlled increasing downward vertical deflection ofa point on said track where said load is applied as the distance fromsaid point to one end of said track increases, wheeled sub-carriageoperatively connected to said operatively deflectable track andconstrained to track along a portion of the length thereof, calibratedspring traction means operatively connected to said subcarriage andoperatively connectable to a cervical or lower back traction applicationm ans on a seated patient.

5. A passive mechanism, for applying traction to a patient, comprisinghinge means, means for operatively connecting one leaf of said hingemeans to a supporting structure, an operationally rigid horizontallyoriented linear structural member in cantilever attachment to therotatable leaf of said hinge, an operationally deflectable monorail,first end of said operationally deflectable monorail operativelyconnected to the rotating portion of said hinge, second end of saidmonorail operatively connected to the free end of said operationallyrigid cantilever member in a manner allowing a limited elasticallycontrolled downward motion of said operatively deflectable monorail, awheel which tracks on said monorail, a traction support meansoperatively attached to the axis of said wheel, calibrated springtraction means operatively at tached to said traction support means,tension transmitting means operatively attached to said traction meansand operatively attachable to a traction application means when saidtraction application means is operatively attached to a patient whensaid patient is operatively positioned with respect to said mechanism.

6. A passive mechanism for applying cervical or lower back traction to aseated patient in accordance with the provisions of claim 2 wherein saidtrack is a monorail consisting of an operationally deflectable resilientlinear member cantilever mounted to said primary carriage means.

7. A passive mechanism for applying cervical or lower traction to aseated patient in accordance with the provisions of claim 2 wherein saidtrack is operationally essentially rigid, first end of said trackconnected to said primary carriage means by a pivotal rotating joint,second end of said track operationally suspended from said primarycarriage by a spring.

8. A passive mechanism in accordance with claim 2 wherein said track, isan operationally essentially rigid structural member, with the edge orsurface which serves as the tracking surface formed in increasingdownward slope in the vertical plane in the direction in which apatients trunk would make a forward bending motion when a patient isusing said mechanism.

9. A passive mechanism for applying cervical and or leg traction to apatient in a :bed equipped with tractionsupport frame, comprising aprimary carriage to provide first coordinate motion in a horizontalplane operatively connected to said traction support frame, a wheeledsubcarriage running along a track mounted on said primary carriage toprovide motion along a second coordinate in a horizontal planeessentially at right angles to said first coordinate, traction meansoperatively attached to said sub-carriage, tension transmitting meansoperatively connected to said traction means and operatively connectableto a traction application means on a patient such that when a patient issetting upright in said bed he may move his head and trunk and leg, thatare in traction, back and forth or sideways under essentially constanttraction,

10. A passive mechanism for applying traction to a patient, comprisingoperational mechanism support means, primary carriage means operativelyconnected to said mechanism support means and free to move from right toleft or forward and backward, structural member operatively connected tosaid primary carriage means, said structural member formed in a verticalplane in a manner providing a rail with increasing downward slope, subcarriage means operatively connected to said structural member andconstrained to track along a portion of said rail, traction meansoperatively connected to said subcarriage means and operativelyconnectable to a traction application means on a patient when saidpatient is operatively positioned with respect to said carriage means.

11. A passive mechanism for applying traction to a seated patient,comprising a chair, a vertical support member operatively connected tosaid chair and extending thence upward, a hinge operatively connected tothe upper portion of said vertical support member, an operationallyrigid horizontally oriented linear structural member in cantileverattachment to the rotatable side of said hinge, an operationallydeflectable linear structural member capable of serving as a monorailfor a wheel, one end of said operationally deflectable monorail memberoperatively connected to the rotating portion of said hinge, saidmonorail operatively connected to said operationally rigid cantilever ina manner allowing a limited elastically controlled downward motion ofsaid operatively deflectable monorail, a wheel which tracks on saidmonorail, a traction support means operatively attached to the axis ofsaid wheel, calibrated spring traction means operatively attached tosaid traction support means, tension transmitting means operativelyattached to said spring traction means and operatively attachable totraction application means when said traction application means isoperatively attached to a patient when a patient is seated on saidchair.

12. A passive mechanism for applying traction to a seated patient,comprising support means operatively connectable to a chair, saidsupport means having a vertical member extending above the back of saidchair when operatively connected thereto, a hinge operatively connectedto the upper portion of said vertical support member, an operationallyrigid horizontally oriented linear structural member in cantileverattachment to the rotatable leaf of said hinge, an operationallydeflectable monorail, first end of said operationally deflectablemonorail operatively connected to the rotating leaf of said hinge,second end of said monorail operatively connected to the free end ofsaid operationally rigid cantilever imember allowing a limitedelastically controlled downward motion of said operatively deflectablemonorail, a wheel which tracks on said monorail, a traction supportmeans operatively attached to the axis of said wheel, calibrated springtraction means operatively attached to said traction support means,tension transmitting means operatively attached to said spring tractionmeans and operatively attachable to a traction application means whensaid traction application means is operatively attached to a patientwhen a patient is seated on said chair.

13. A passive mechanism for applying cervical traction to a seatedpatient, comprising calibrated spring traction means operativelyadjustably connectable to a traction application means on a patient;said traction means operatively connected to the frame of a subcarriagemeans; a wheel and axle operatively mounted to said frame of saidsub-carriage means; a primary carriage comprising an operationally stiffelastic cantilever member and an operationally elastically deflectablecantilever monorail oper atively connected to a common cantileversupport base and said base operatively connected to a rotatable firstleaf of a hinge; the free end of said cantilever monorail connected tothe free end of said stiff cantilever member by means of a firstflexible tension transmitting member,

said first flexible tension transmitting member serving as a deflectionlimiter to the free end of said monorail along which said sub-carriagemeans moves on said wheel and axle; a second flexible tensiontransmitting means the tWo ends of which are adjustably translationallyconnected respectively to said operationally stiff cantilever member andto said monorail between said sub-carriage and said hinge, saidadjustable connections of said ends of said second flexible tensiontransmitting means serving as a safety device against possible breakageof said cantilever monorail and as a rear position limit of saidsub-carriage; the second leaf of said hinge operatively connected to avertical support member; said vertical support member operativelyconnected to a patient seating means; said patient seating means, saidvertical support member, said primary carriage and sub-carriage, saidcalibrated spring traction means all operating in coordination with saidtraction application means on a seated patient so that said seatedpatient may carry out normal seated activities under essentiallyconstant low inertia traction.

References Cited UNITED STATES PATENTS 821,116 5/ 1906 Nunamaker 297-275935,170 9/1909 Smith 581 1,269,734 6 1918 Noland 584 1,731,709 10/ 1929Cropsey 592 2,166,229 7/ 1939 Anderson l2887.2 2,714,885 8/1955 Uhland128--75 2,772,675 12/1956 Simmons 12887.2 2,843,114 7/1958 Hall 128-752,929,375 3/1960 Spinks l28 84 2,938,695 5/ 1960 Oiampa 128-75 3,060,92910/ 1962 Zivi 128-75 3,105,489 10/1963 Zivi 128-75 FOREIGN PATENTS726,666 3/ 1932 France. 830,264 5/ 1938 France.

L. W. TRAPP, Primary Examiner.

